#include <stdio.h>

int main() {
	int a,b,c;
	scanf("%d%d%d",&a,&b,&c);
	if (a+b>c && a+c>b && b+c>a) {
		if (a==b && b==c) printf("This is equilateral triangle.\n");
		else if (a==b || b==c || a==c) printf("This is isosceles triangle.\n");
		else printf("This is normal triangle.\n");
	} else printf("This is impossible triangle.\n");
	return 0;
}
